Antimicrobial Activities of Co (III), Mono and Tri-nuclear Ni Complexes Containing Schiff base Functionalized Imidazolium based Ligands

Abstract

We reported the antimicrobial activities of cobalt and nickel complexes containing imino-NHC ligands. Complex 2 was synthesized by direct reaction of the insitu generated free carbene from 2-[2-(3-benzylimidazol-1-yl)ethyliminomethyl]phenol ligand with NiCl2 diglyme while complexes 3-5 were previously reported as catalysts in the transfer hydrogenation reaction of ketones. The compounds 1-5 were screened for antimicrobial sensitivity test against four gram-negative bacteria Escherichia Coli (E-coli), Shigella, Klebsiella Pneumoniae (K. Pneumoniae) and Salmonella Typhi (S.Typhi) and a gram positive bacteria Staphylocossus aureus (S.aureus). At a varying concentrations of 100, 200, 300, 400 and 500 µg/mL, significant activities were recorded using disc diffusion methods. The cobalt complex 3 was found to have higher activities compared with the corresponding nickel complexes and among the three nickel complexes, nickel complex with pyridine as wingtip was found to be more active than the one with a benzyl group. Similarly, the nickel centre with mononuclear was found to be more active than the tri-nuclear nickel complex.  Except for the cobalt complex 3 no activity was recorded against S. typhi for all the nickel compounds.